Treatment of hydrocarbon stocks with sodium



2,712,211 TREATMENT or HYDROCARBON srocxswrrn sonnm Arthur S. Hawkes, Royal Oak, and Donald 0. Remter, Detroit, Mich., assignors to Ethyl Corporation, New York,.N. Y., a corporation of Delaware No Drawing. Application May 28, 1953, Serial No. 358,171

5 Claims; (Cl. 19626) This invention relates to the-treatment of hydrocarbon stocks and is particularly concerned with improving the storage stability, gum content, and sulfur content of these stocks.

The problem of improving the stability characteristics of hydrocarbon stocks and petroleum fractions has become increasingly important, particularly in recent years, due to the fact that the utilization of catalytic cracking has made the problem of stability, reduction of gum formation, and desulfurization of fuels more significant. Heretofore, various processes have been utilized particularly for desnlfurizing petroleum distillates, 'but these processes have had considerable disadvantage and have been restricted in their usage. For example, treatment of hydrocarbon stocks with alkali metals has been investigated, but this process has found limited usage inasmuch as high temperatures-and high pressures have beenrequired, and the reactivity of the residues obtained is of. such a nature that. disposal thereof is quite hazardous. Further, in order to acquire the desirable characteristics of the fuel, it has been necessary to utilize quantities of the alkali metal in excess, of, the equivalent amount; of. sulfur present in the charge stock. This excess amount of alkali metal is therefore not considered practicable-in that the economics of the process are not favorable. A further disadvantage of this process has been that the gum-reducing tendencies of the process have not been appreciable, and in addition the stability qualities of the fuel have not been obtained. High gum content is not desirable in the fuels, particularly when they are to be utilized in internal combustion engines, since they will form coatings and. result in valve sticking and other undesirable features inoperation. High sulfur content similarly is not considered desirable since the sulfur content contributes to wear or corrosion of the, integral parts in an internal com bustion engine.

It is an object, therefore, of the present invention to' overcome the difliculties experienced in the'prior art andto provide a process for improving the stability characteristics of hydrocarbon stocks.

these petroleum distillates. A still further object is to treat hydrocarbon stocks in a manner which will not produce a hazardous reactive residue. These and other objects of this invention will become apparent from the'discussion hereinafter.

The process of the present invention comprises treating hydrocarbon stocks With catalytic quantities of a light metal to improve the characteristics of the stock, such asgum and sulfur content, stability, and color. Surprisingly, we have found that upon treating hydrocarbon stocks with a proportion of light metal less than the stoichiometric equivalent of the amount of sulfur contained'in the stock, its storage stability can be considerably improved, the gum content essentially eliminated, and the sulfur content diminished to provide a desirable product for its use in internalcombustion .enginesor for blending with other fuels.

A further object of this invention is to provide a novel process for desulfurizing;

2,772,211 Patented Nov.- 27, 1956 As one means of achieving this result, a dispersion of a light metal in heavy alkylate is introduced into a stream of. a hydrocarbon stock. This mixed stream is then passed to a preheater, where it is heated to adesignated temperature; from the preheater the streamis passed to a reactor at a higher designated temperature. The stream is then passed to a second heat exchange wherein the liquids are vaporized at a reduced pressure, and suflicient heat is-maintained to pass the stream in the vapor state,

entraining the nonevolatile components, to the flashing chamber. Upon entry into the flash chamber the vapors and non-volatile residues are impelled against a baffle, and the vapors pass out of the flash chamber, whereby the non-volatile sulfur compounds, gums, and: gumforming constituents are retained in the flash chamber and discharged from the bottom. The vapors, now essentially void of these undesirable components, are then condensedfor further processing or for use in blending with otherfuels, Many arrangements and combinations of the-foregoing and alternate embodiments Will be apparent to those skilled in the art.

We havefound that We can treat the hydrocarbon stocks according to the process of our invention atcomparatively moderate temperatures and pressures. In general, We prefer to use. temperatures being between about a 150 and 500 E, the contact time at this temperature being. between about 0.5 and 40 minutes. The pressures utilizedwill vary depending upon the particular temperature used and the particular stock which 'is charged. However, we generally prefer to use pressures of between about 300 and 750 pounds per square inch. The flash vaporization step of our process is preferably conducted at temperatures between about 200 and 500 F. and at atmospheric pressure. It is not intended that we be restricted to the foregoing temperatures and pressures but that they may be varied from these limits. For example, the process of our invention is applicable to temperatures up to and including about 1000 F. and pressures up to andincluding about 2000 p. s. i. However, substantialvariation beyond the limits mentioned is not desirable inasmuch as we have found that as the temperature is increased the quality of the product obtained is decreased; that is, higher temperatures produce additional cracking which will result. in increased gum formation and decreased storage stability. Further, the contact time may be extended beyond the limits of 0.5

to 40 minutes; that is, the treatment may be for several dispersed in an inert medium such as in the hydrocarbon stock, heavy aviation alkyla-te, toluene, benzene, the xylenes, and other materials which are suitable for this purpose. It is not necessary that the dispersion be preprepared. It may be prepared in situ using the hydrocarbon stocks as the dispersing medium. Although the particle size of the dispersed light metal is not critical;

' we prefer to use particle sizes of substantially below ticularly advantageous in that lower temperatures can'be utilized for maintaining the dispersion properties of the tweenthe particles'and the stock being treated. A fur- Y metal have been utilized'prior to this invention, and therefore, the processes have had limited scope due tothe fact that the residues obtained are reactive and hazardous. For example, when sodium'has been used," it is known that sodium on contact with Water produces hydrogen which is subject to ignition instigated by the heat of the reaction, a condition untenable in refinery operations. We have now found that catalytic quantities of the light metal can be used which result in a non-reactive residue and therefore eliminate this hazard. In general, we utilize less than the equivalent (that is, stoichiometric) amount of light metal required for complete sulfur re- .moval.

Specifically, when the light metal is an alkali metal, we

prefer to use less than two moles of the alkali metal per mole of sulfur contained in the stock. When the light metal is an alkaline earth metal, we prefer to use less than one mole ofthe alkaline earth metal per mole of sulfur contained in the stock. In utilizing these quantities" it 'has been found that a considerable reduction in gum content and an increase in the stability is obtained concurrently with the reduction in the sulfur content. Further, the product obtained is colorless, which is also a desirable feature of the finished product.

The hydrocarbon stocks or petroleum distillates which we can treat according to the process of our invention are those materialscommonly known to the petroleum refinery industry. We have found this process to be particularly adaptable to the so-called catalytically cracked naphtha fractions. This fraction is known to contain the major portion of gum-forming constituents and high sulfur content. 'Bytreatmentlof thi'sfraction according to the process of our invention, the gums, gum forming constituents, and sulfur compounds are removed to a satisfactory percent, and the product obtained is par- .ticularly suitable for use in blending with' other fractions or for use ininternal combustion engines.v Other; frac-' tions, such as, for[example, the, gasoline and diesel'fracz.

tions,for' crudes may also be treated according'tothe process of the present invention..- Further, these stocks may also be previously washed Withcaustic, and in' general .this is preferredrinasmuch' as it is known that, caustic washing reduces the phenolic content and other undesirable. constituents of these stocks. V a a Typical examples for carrying out the'process of our.

invention are as follows, wherein all parts and percentages are by weight. v r Example I To a stream o f a caustic'washed hydrocarbon stock, feed rate 0.25 to 0.5 part per minute, having a boiling range'of between 200 and 500 F., a dissolved gum conreact with the sulfurwas utilized. The stream was passed through a preheater maintained at a temperature of about 300? and then transmitted to a reactor ,which Wasata temperature of about 400f F. 3 The total contact time was about 05 minute. The stream' was then passed through alflash vaporizer which was maintained at'a'temperature of about 425 F. The vapors were flashed ofi in a flash chamber,-and the gums, gum-forming constituents, .and sulfur compounds remained as residues. These residues showed no activity when mixed with water. The pressure maintained in the system was about 400 pounds per square inch with the exception of the flash vaporizer, which was maintained at atmospheric pressure. The product vapors had a dissolved gum content of 0.9 mgs. per 100 mls., a copper dish gum content of 3.2 mgs. per 100 mls., and the sulfur content was found to be'0.306.per cent. The dissolved gum content was; determined by ASTM procedure D381-50, and the copper dish gum content was determined by ASTM procedure D910-50T. The sulfur content was determined 'by ASTM procedure D90-50T. 7

Other examples ofthe efficiency of the process of this invention are shown in the following table, wherein the equipment utilized was essentially the same as in the i preceding example, but the contact time, reactor temperature, and amount of sodium utilized were varied.

Reaction Gum Content Sulfur, Percent Na (Based Dissolved Copper Percent on Charged Stock) Time, Temp., Gum, Dish By Mins. F. rug/100 Gum, Weight 1 m1. mg /100 0 5 400 0. 9 3. 2 0. 306 40 400 0. 0 2. 4 0. 287 0. 5 200 1. 6 8. 0 0. 307 40 200 0. 6 5. 0 0.25 1 0 400 1.2 0.339 Charge Stock 54. 2 427 O. 44

Similarly other alkali or alkaline earth metals can be utilized according to the process of our invention. Forexample, the hydrocarbon stocks can be treated .withpotassium either in a dispersed form or in a finely divided state. Likewise, we can use calcium, lithium, rubidium,

tion, fractionaldistillatiom'and similar processesyhowever, we prefer to use the flash vaporization step." It is also understood that the streams may be preheated before reactor.

entrance into either the reactor or the flash vaporizer; that is, the mixed stream of hydrocarbon stock and lightmetal may be preheated if desired to atemperature of between about 150'and 400 F.'b'efore entry'into' the} Likewise, the streamsleaving the reactor may I .be reheated to temperatures between about 300 and-500 F., or they may be maintained at the temperature the stream has obtained in ithe reactor by appropriate-insu lation of feed lines. Further, our process is equally adapt-;

' able to batch or continuous. operations.

' Similarly, the process of increasing the storage stability, reducing gum formation and sulfur content will be applia The process of-the present invention will find particular usage in the petroleum refineryindustry for the production ofgasoline range fuels, diesel fuels, and the like.

cable to treatment of crude hydrocarbon stocks. In addition, the novel process of our invention will provide a method of treating hydrocarbon stocks' with an" active 'metal in'which'the' hazard of obtaining a reactive residue has been eliminated;- These andpother .uses will become apparent to'those skilled. in the art.

Having thus described the process of our invention, it} is not intendedthat we-belimited except as, noted in;-the;

appended ui ,5 v

drocarbon stock having gum-forming components and a low sulphur content with a finely-divided metal selected from the group consisting of alkali and alkaline earth metals comprising treating said stock with from 0.25 to 0.5% by weight of said metal based upon the Weight of said stock for a period of between about 0.5 to 40 minutes at a temperature from 200 to 500 F.

2. The process of claim 1 wherein said finely-divided metal is sodium of particle size less than 20 microns dispersed in a hydrocarbon liquid which is essentially inert to said sodium, said hydrocarbon stock is catalytically cracked naphtha having less than about 0.44% by weight of sulphur and said sodium is employed in amount between 40 to 80% by weight of the stoichiometric amount required to react with the sulphur content of said stock.

3. The process of treating an essentially anhydrous gasoline range hydrocarbon feed stock having gum-forming components and a low sulphur content whereby the gum-forming tendencies are virtually eliminated and appreciable reduction in sulphur contaminant is accomplished comprising blending a preformed dispersion of an alkali metal in a hydrocarbon liquid essentially inert to said metal with said feed stock in proportions providing from 0.25 to 0.5 percent by weight of said metal based on the weight of said stock, heating said blend under continuous flow conditions at a temperature from 200 to 500 F. for a period from 0.5 to 40 minutes while maintaining under supra-atmospheric pressure suflicient to prevent appreciable vaporization of the gasoline range hydrocarbon, then flash vaporizing the gasoline range hydrocarbon at substantially atmospheric pressure and separating the so formed vapors and non-volatile residues.

4. The process of treating an essentially anhydrous gasoline range hydrocarbon feed stock containing gumforming components and a low sulphur content whereby the gum-forming tendencies are virtually eliminated and appreciable reduction in sulphur contaminant is accom plished, comprising (a) forming a dispersion of sodiun metal substantially below about 20 microns in size in 2 portion of said gasoline range hydrocarbon under conditions at which substantially no reaction occurs, (b) blending said preformed dispersion with the gasoline range hydrocarbon in proportions providing between to 8( percent by weight of the stoichiometric amount of sodiun required to completely convert the sulphur to sodiurr sulphite, (c) heating said blend under continuous flovs conditions for a period between 0.5 to 40 minutes at 2 temperature from 200 to 500 F. while maintaining sufficient pressure to maintain substantially all the feed stock in the liquid phase, (d) flash vaporizing the gasoline range hydrocarbon at substantially atmospheric pressure and separating the so formed vapors and non-volatile residues.

5. The process of claim 4 wherein said gasoline range hydrocarbon is catalytically cracked naphtha treated 01 a period of 0.5 minute.

References Cited in the file of this patent UNITED STATES PATENTS 534,295 Suckert Feb. 19, 1895 1,801,412 Carlisle Apr. 21, 193] 1,864,687 Fields June 28, 1932 1,865,235 Cross June 28, 1932 1,938,670 Sullivan et al Dec. 12, 1933 1,938,671 Sullivan et al Dec. 12, 1933 1,938,672 Ruthrutf Dec. 12, 1933 1,952,616 Vose Mar. 27, 1934 1,962,698 Vose June 12, 1934 2,058,131 Carlisle Oct. 20, 1936 2,078,468 Stratford Apr. 27, 1937 2,614,967 Vanderbilt et al. Oct. 12, 1952 

1. A PROCESS FOR TREATING AN ESSENTIALLY ANHYDROUS HYDROCARBON STOCK HAVING GUM-FORMING COMPONENTS AND A LOW SULPHUR CONTENT WITH A FINELY-DIVIDED METAL SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METALS COMPRISING TREATING SAID STOCK WITH FROM 0.25 TO 0.5% BY WEIGHT OF SAID METAL BASED UPON THE WEIGHT OF SAID STOCK FOR A PERIOD OF BETWEEN ABOUT 0.5 OT 40 MINUTES AT A TEMPERATURE FROM 200 TO 500* F. 